11. These industries cover products such as industrial valves, butterfly valves , valve actuators, relief valves, cocks. 12. There are different kinds of butterfly valves , each adapted for different pressures and different usage. 13. A lug-style butterfly valve used in dead end service generally has a reduced pressure rating. 14. The zero-offset butterfly valve , which uses the flexibility of rubber, has the lowest pressure rating. 15. A "'butterfly valve "'is a valve which can be used for isolating or regulating disk. 16. Today, the waste water portfolio especially includes butterfly valves as well as venting and bleeder valves. 17. The American Water Works Association issued a specification for the butterfly valve , AWWA C-504, in 1954. 18. Another innovation for the Henry Pratt Company was the design of the first rubber-seated butterfly valve . 19. Each throttle shaft has a butterfly valve that controls how much air gets into the engine. 20. If the pipeline contains butterfly valves , or reduced port ball valves, the pipeline cannot be pigged.
